Not Applicable
This invention relates to a web handling apparatus. It relates more particularly to a compact, user friendly web splicer which is particularly useful in but not limited to the packaging industry.
1. Field of the Invention
While we will describe the invention in the context of a zero speed splicer of the roll-over-roll type, certain aspects of the invention are equally applicable to other types of splicers including but not limited to roll-beside-roll and turret-style splicers and even to certain web winders.
The web splicers of interest here are well known in the art. Generally, these splicers have a running web roll and a ready web roll positioned one over the other. Web from the running roll is conducted through a splicing head into a web accumulator and then to web consuming apparatus, such as a bag making machine, which establishes the overall machine centerline. Typically, the web, which is often of a plastic material, travels into the web consuming machine at a moderate line speed of 50 to 350 ft/min. When the ready roll is about to expire, a splice sequence is initiated which decelerates and stops the running web at the splicing head, splices the already prepared leading end of the ready web to the now stationary running web and separates the spliced segment of the running web from its substantially empty roll core, following which the ready web is brought up to line speed. During this splice sequence, web is drawn from the accumulator to feed the web consuming machine so that there is no interruption in the web supply to that machine. After splicing, the accumulator is refilled with web from the ready roll and the empty roll is replaced with a fresh roll which then becomes the ready roll for the next splice sequence.
The various steps in the splice sequence may be carried out manually for splicers which handle moderate web speeds, as is the case here. In high-speed machines, those steps may be performed automatically. In any event, it is essential that the splicing operation take place in a reliable and consistent manner to avoid web breaks that could interrupt the web supply to the web-consuming machine.
2. Description of the Prior Art
The typical splicer used in the packaging industry is not particularly compact, efficient or user friendly. Many splicers have removable unwind shafts for supporting the rolls. In order to load a new roll into the splicer, a loose shaft must be threaded through bushings fitted in the ends of the roll core and the roll manually lifted up into the machine so that the unwind shaft seats in suitable fixtures therein. Thus when web is drawn from the roll, its core will rotate freely relative to the shaft.
When each new roll is inserted into the machine as aforesaid, it is not necessarily aligned with the machine centerline established by the downstream web-consuming machine. Therefore, conventional splicers invariably incorporate means for shifting the web roll in one direction or the other on its shaft (side lay adjustment) so that it is aligned with the machine centerline. Conventionally, this is accomplished by monitoring the lateral position of the web leaving the splicer using web edge sensors or the like and comparing that position with a desired centerline position in a feed back arrangement that controls an actuator able to adjust the side lay of a new roll in order to align the web from the new roll with that centerline.
The problem with this known procedure is that a large amount of web is stored in the splicer""s accumulator. Therefore, if a new roll is not aligned with the machine centerline following a splice sequence, due to the length of web stored in the accumulator, there is a relatively long delay between the detection of the misalignment and the correction of the roll position on its shaft. This means that an appreciable length of misaligned web may be delivered to the web-consuming machine which could give rise to downstream problems resulting in web breakage. Bearing in mind that such misalignment can occur each time a new roll is loaded into the splicer, there is an appreciable potential for web wastage and machine downtime.
Conventional splicers used in the packaging industry have another drawback in that it is unnecessarily difficult to prepare the leading end of the ready web in preparation for a splice. This is because, as a rule, the region of the splicer where the splicing takes places, i.e., at the splicing head, is quite congested and the webs themselves are not presented in a way to facilitate the trimming of the leading edges of the ready webs and the application of the required splicing tapes. Accordingly, the splice preparation procedure takes longer than it should and there are often variances in the way that the splice preparation steps are carried out with the result that the quality of the resultant splices is not consistent. Obviously, a poor quality or defective splice can also cause web jams and web breakage in the downstream machine thereby reducing the throughput of that machine.
Accordingly, the present invention aims to provide a splicer which is especially suitable for use in the packaging industry, although not being limited to that application.
Another object of the invention is to provide a splicer of this type which is relatively compact and which has a small footprint.
A further object of the invention is to provide a zero speed splicer of the roll-over-roll type which facilitates the loading of fresh rolls into the splicer.
An additional object is to provide a splicer which has non-rotating roll shafts.
Another object is to provide such a splicer which minimizes the amount of misaligned web delivered to a downstream web-consuming machine following each splice.
Yet another object of the invention is to provide a web splicer of this general type which enables an operator to easily, efficiently and consistently prepare the webs that are to be spliced.
A further object of the invention is to provide a zero speed web splicer which produces high quality butt and lap splices between webs on a consistent basis.
Yet another object of the invention is to provide a splicer with the loading benefits of a cantilevered splicer and the space efficiency of a front-loading splicer.
An additional object is to provide a splicer able to easily make lap or butt splices with out modification of the splicing head.
A further object is to provide a zero speed splicer which utilizes a web roll surface drive instead of a traditional braking system.
Another object of the invention is to provide such a splicer with a roll surface drive which is used for web tension generation, stopping the web during splicing, roll acceleration after the splice and alignment of a running web""s preprinted image with the image on a preprinted ready web.
A further objective is to provide a splicer with a roll surface drive which, when used in conjunction with a downstream web position sensor, identifies the last web segment on the expiring roll core, stops the running web and then backs up the web so as to rewind the web onto the core until the running web""s preprinted image is aligned with the image on the ready web.
Other objects will, in part, be obvious and will, in part, appear hereinafter.
The invention accordingly comprises the feature of construction, combination of elements and arrangement of parts which will be exemplified in the following detailed description, and the scope of the invention will be indicated in the claims.
Briefly, the invention is implemented in a roll-over-roll splicer which splices at zero speed. However, as noted at the outset, certain aspects of the invention may be implemented in other types of splicers and even to some web winders.
The present splicer incorporates a conventional web accumulator so that web can be delivered uninterruptedly to a downstream web consuming machine of the type used in the packaging industry, e.g. a bag making machine. The two web rolls may be rotatably mounted to a pair of special swing-out unwind shafts normally positioned above and below and parallel to the splicing head. One end of each shaft is hinged to a side wall of the splicer so that the shaft can be swung out to an accessible loading position in front of the splicer where an operator can load a new roll fitted with end bushings into the splicer simply by sliding that roll endwise onto the shaft. Following that, the shaft and the new roll thereon may be swung to a closed operative position in preparation for the next splice.
In a preferred embodiment of the splicer, the upper unwind shaft is connected to the splicer side wall by way of a lifting device including a vertically movable carriage. When the upper shaft is in its open loading position, the carriage can be moved by suitable motive means (mechanical, pneumatic or hydraulic) between a lower loading position which places that shaft relatively close to the floor and an upper loading position which locates that shaft at its normal elevation above the splicing head. Thus by appropriately raising the carriage, an operator can load a new roll onto the upper unwind shaft quite easily and without any heavy lifting and so suffers minimal back and arm strain when loading a new roll into the splicer. Hence, the loading process is easier, safer and requires less exertion on the part of the operator.
Also as we shall see, the splicer incorporates a unique splicing head employing mirror-image upper and lower splicing sections for splicing the webs from the upper and lower rolls. When web from the lower roll is being delivered via the accumulator to the web consuming machine, the upper splicing section is used to prepare the leading edge of the web from the upper roll so that during the next splice sequence, that leading edge will be spliced to the trailing end of the web from the expired lower roll. Conversely, when web from the upper roll is being conducted to the web consuming machine, the lower splicing section is available to prepare the leading end of the web from the lower roll so that it can be spliced to the trailing end of the web from the upper roll during the following splice sequence. After each splice sequence or cycle, the unwind shaft supporting the empty roll is moved to its loading position and the roll core thereon is removed and replaced with a new roll following which that shaft is returned to its closed, operative position, and so on.
Preferably, to minimize the duration of the splice sequence and the amount of web that has to be stored in the accumulator, the splicer includes upper and lower roll surface drives each of which may accelerate a new or ready roll following a splice so that the web therefrom may be brought up to line speed in a minimum amount of time. Actually, the web is usually fed into the accumulator at a speed somewhat greater than line speed for a selected period of time to refill the accumulator to serve the needs of the web-consuming machine during the next splice sequence.
As we shall see, in the present splicer, instead of shifting a new roll on its shaft in order to align the web drawn therefrom with the machine centerline, the roll is set at a substantially fixed position along the shaft and the entire splicer including the accumulator is moved laterally relative to the machine centerline as necessary to align the new web with the machine centerline. More particularly, the splicer housing is moved laterally relative to a fixed base by an actuator that is connected in a feedback loop that responds to the output of a downstream web sensor that senses the side lay of the web leaving the splicer. This means that there is minimal delay between the detection of an off-center web and the correction of the side lay of the running web being drawn from the new web roll. Therefore, the amount of misaligned web following each splice sequence is minimized which, in turn, minimizes downstream problems involving the moving web.
Further as will be described in detail, the present splicer has a splicing head which gives the operator ready access to the leading end of the web from the ready roll, be it the upper roll or the lower roll, in order to prepare that end for splicing. Furthermore, the head is designed to splice the leading end of the ready web to the running web in a precise and consistent manner using either a butt splice or a lap splice. Therefore, there is minimal likelihood of the spliced-together webs parting during their travel from the splicer through the downstream web-consuming machine or causing jams or other problems in that machine.
All of the foregoing features combine to produce a web splicer which is optimized to suite the needs of the packaging industry.